Phase transformation from In2S3 to CuInS2 using ultrasonic spray pyrolysis

In this work systematic conversion of In2S3 into CuInS2 was studied using ultrasonic spray pyrolysis (USP) system. The ternary compound group of I-III-VI is important for solar cell because In2S3 acts as a buffer layer, while CuInS2 acts as an absorber layer in solar cell. CuInS2 thin films were synthesized by adding certain amounts of copper salt in the solution containing 0.06 M indium chloride and 0.36 M thiourea. In the absence of copper, the above solution forms In2S3. The copper salt added solution was ultrasonically sprayed on a glass substrate kept at 350°C. For synthesis of n-type and p-type CuInS2, copper chloride with concentrations of 0.04 M and 0.06 M was added, respectively, in the solution containing indium chloride and thiourea. These films were characterized by X-ray diffraction (XRD), Raman spectroscopy, UV-Vis spectrophotometer, Hall effect measurement, etc.